The present invention relates to a seat belt retractor with a load limiter.
1. Background of the Invention
A seat belt system prevents a vehicle occupant from sustaining injuries in a crash as a result of colliding with the interior structure of the vehicle. In a crash, a locking device locks the seat belt webbing such that further extraction of the seat belt webbing due to the forces acting upon the vehicle occupant is prevented and the vehicle occupant is held in the seat through the belt force achieved by the locking.
2. Prior Art
In known seat belt retractors, it has been shown to be a disadvantage that the belt force is independent of the characteristics of a particular crash and/or the vehicle occupant. In these cases the belt force is determined on the basis of mean values, for instance the average weight of vehicle occupants or mean crash values. If the vehicle occupant, however, weighs less than the average weight, even though the belt force indeed is able to prevent the person from sustaining an injury due to colliding with a component inside the vehicle, the belt force can be too great for this person and cause him/her harm.
A seat belt retractor according to the present invention has a locking device with at least one gear that is reversibly lockable by at least one lock operating device, and has at least one energy absorbing device. Therefore, the belt force resulting from the locking of the seat belt retractor in a crash can follow the crash pulse, or that parameters dependent on people, such as for instance the weight of the vehicle occupant, can be taken into account. In particular it is possible, after an initially high level of belt force, to decrease the latter to a reduced level. The seat belt retractor can be an automatic retractor.